Method of preparing trialkyl tetrathiophosphates

Abstract

Trialkyl tetrathiophosphates are prepared by contacting a dialkyl sulfide with phosphorus pentasulfide according to the following theoretical reaction scheme:

What is claimed is: 
     
       1. A method of preparing compounds of the formula:   (R.sup.1 S).sub.x (R.sup.2 S).sub.y P(S)                   (I)     wherein x+ y= 3; R 1  and R 2  are the same or different and are selected from the group consisting of C 1  -C 18  straight-chain or branched alkyl and cycloalkyl of 5 to 6 carbons in the ring and the C 1  -C 4  alkyl substituted derivatives thereof; comprising contacting under at least an autogenous pressure at a temperature of from about 150° C. to 300° C. a reactant selected from the group consisting of dialkyl sulfide reactants of the formula:     R.sup.1 SR.sup.2                                           II     wherein R 1  and R 2  are as defined above with a phosphorus pentasulfide reactant of the formula:     P.sub.4 S.sub.10.     
     
     
       2. The method of claim 1 wherein R 1  and R 2  are the same or different and are selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tertbutyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, cyclopentyl, cyclohexyl and ethylcyclohexyl. 
     
     
       3. The method of claim 1 wherein R 1  and R 2  are the same and are selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, cyclopentyl, cyclohexyl and ethylcyclohexyl. 
     
     
       4. The method of claim 1 wherein said autogenous pressure is between about 1 and about 300 atmospheres. 
     
     
       5. The method of claim 1 wherein said reactants are employed in stoichiometric amounts according to the following equation:   6R.sup.1 SR.sup.2 + P.sub.4 S.sub.10 → 4(R.sup.1 S).sub.x (R.sup.2 S).sub.y P(S)     wherein x, y, R 1  and R 2  are as defined in claim 1.